1. Field of the Invention
The present invention relates to a camera system having a camera body and a photographing lens which is detachably attached to the camera body, and having a communication system between the camera body and the photographing lens.
2. Description of the Related Art
Power zoom lenses (motorized zoom lenses) with an image size tracking mode, in which the camera can automatically zoom the lens to constantly capture the object at a predetermined image size regardless of the distance to the object, within the constraints of the focal length range, are known in the art. In recent camera systems having a camera body and an interchangeable photographing lens which is detachably attached to the camera body, if the above-described type of power zoom lens with the image size tracking mode is employed, the camera body prepares only data necessary for a controller of the photographing lens to perform operations thereof in the image size tracking mode, and transmits such data to the photographing lens together with various control commands.
However, according to such a data transmission system of the camera system, if the development of an interchangeable photographing lens having one or more additional functions (e.g., a lens autofocus function) is intended, the camera body to which the photographing lens is mounted will need to prepare camera-status data necessary for the photographing lens to operate for each of all the functions of the photographing lens. This complicates various communication processes and controls of the camera system. On the other hand, if an interchangeable photographing lens having one or more new functions is mounted to a conventional type camera body, it is often the case that such new functions cannot be used and may cause the camera body to malfunction. Accordingly, the development of an interchangeable photographing lens having one or more new functions which maintains compatibility with existing camera bodies is difficult in conventional camera systems. In addition, the development of a camera body which can maintain compatibility with a newer developed interchangeable photographing lens is also difficult in conventional camera systems.
The present invention provides a camera system having a camera body and a photographing lens which is detachably attached to the camera body, wherein the camera system is designed to increase the degree of freedom in the development of the photographing lens with one or more additional new functions, and the general versatility of the camera body and the photographing lens is increased.
For example, in an embodiment, a camera system having a camera body and a photographing lens, which can be mounted to and dismounted from the camera body, is provided, wherein the camera body includes a determining device which determines a type of the photographing lens in accordance with data received from the photographing lens; and a body controller which has a function to send body data and individual function data to the photographing lens, wherein each of the individual function data is required for a corresponding function that the photographing lens possesses. The body controller sends all the body data to the photographing lens regardless of the type of the photographing lens, and sends a portion of the individual function data which is associated with the type of the photographing lens to the photographing lens.
The body controller can send all the body data to the photographing lens at regular intervals, and selectively send the individual function data to the photographing lens in accordance with the type of the photographing lens.
It is desirable for the photographing lens to include a lens controller, which can communicate with the body controller, wherein the lens controller sends lens type data, which indicates the type of the photographing lens, to the camera body.
If the body controller receives the lens type data output from the lens controller, the body controller can send corresponding the individual function data to the photographing lens.
The body data can include fundamental data of the camera body.
The body data can include data for a power saving operation.
In another embodiment, a camera body is provided, to which a photographing lens can be mounted and dismounted, including a determining device which determines a type of the photographing lens in accordance with data received from the photographing lens and a body controller which has a function to send body data and individual function data to the photographing lens, wherein each of the individual function data is required for a corresponding function that the photographing lens possesses. The body controller sends all the body data to the photographing lens regardless of the type of the photographing lens, and sends a portion of the individual function data which is associated with the type of the photographing lens to the photographing lens.
If the body controller receives the lens type data output from the lens controller, the body controller can send corresponding the individual function data to the photographing lens.
It is desirable for the body controller to send all the body data to the photographing lens at regular intervals, and selectively send the individual function data to the photographing lens in accordance with the type of the photographing lens.
In another embodiment, a photographing lens is provided, which can be mounted to, and dismounted from, a camera body, the camera body having a body controller which has a function to send body data and individual function data to the photographing lens, wherein each of the body data indicates an operating status of the camera body, and wherein each of the individual function data is required for a corresponding function that the photographing lens possesses, the photographing lens including a lens controller which can communicate with the body controller, and can send lens type data which indicates the type of the photographing lens to the camera body.
The present disclosure relates to subject matter contained in Japanese Patent Application No.2001-54542 (filed on Feb. 28, 2001) which is expressly incorporated herein by reference in its entirety.